how to fix P0420 error code on Tesla Model 3 Highland (2024-present)

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the vehicle's battery to ensure safety during repairs.
• Allow the vehicle to cool down to avoid burns.

2. Inspect and Replace Oxygen Sensors

• Sub-steps:
  1. Locate the upstream and downstream oxygen sensors.
  2. Disconnect the electrical connectors from both sensors.
  3. Use an O2 sensor socket to remove the sensors from their respective locations.
  4. Install new oxygen sensors, ensuring they are torqued to the manufacturer's specifications (typically around 30 lb-ft).
  5. Reconnect the electrical connectors.

3. Inspect and Replace the Catalytic Converter (if necessary)

• Sub-steps:
  1. Locate the catalytic converter and inspect for physical damage or excessive carbon buildup.
  2. If replacement is needed, remove the exhaust bolts securing the catalytic converter using a socket set.
  3. Carefully detach the catalytic converter from the exhaust system.
  4. Install the new catalytic converter, ensuring proper alignment and tightening bolts to manufacturer specs (approximately 30 lb-ft).
  5. Reconnect any heat shields or components that were removed.

4. Reconnect Battery and Clear Error Codes

• Sub-steps:
  1. Reconnect the vehicle's battery terminals.
  2. Use the OBD-II scanner to clear the P0420 error code.
  3. Start the vehicle and allow it to reach operating temperature.